Piston and method of making the same



April c. H. WILLS 2,198, 8

PISTON AND METHOD OF MAKING THE SAME Filed'Jan. 30, 1957 INVENTOR.

- G/l/LD Hfl/YOLD W/LL s. BY zwafi @L ATTORNEYS.

Patented Apr. 30, I946 98,8

PISTON AND METHOD or MAKING THE SAME ChildHarold Wills, Grosse Pointe' Farms, Mich.

assignor to Chrysler Corporation, Highland Park, Mich, a corporation of Delaware Application January 30, 1937, Serial No. 123,117

2 Claims. (Cl. 309-9) I) cylinder, improved gassealing, and improved Opening 13 coaxialwith the piston axis for rewearing characteristics with a minimum of fricceiving the head B as will be presently apparent. tion losses. The outer grooved end of the skirt and flange I2.

lAnother object is to provide a composite piston in the present embodiment, are connected by the having its parts held together in assembled conannular margin p on 14 Of e i face 5 dition in an improved manner, preferably witliof the piston, together with strengthening ribs l5. 15

out the use of screws, bolts or other fasteners The head B comprises a unitary casting having which are objectionable for many recognized a mainannularhead portion it formed with the reasons. inwardly extending bosses l'l provided with An additional object is to provide a piston asaligned op ni l' a pte t accommodate a 0 sembly comprising a solid cylindrical skirt portion piston pin l8 for articulation to a connecting rod adapted to carry one or more sealing rings, the I 9. The underface of the head portion i6 is head portion being provided with the piston pin ribbed at 20 transversely to the axis of openings boss or bosses disposed within the skirt portion II. An annular cylindrical portion 21 joins head and free from connection therewith. Such an portion IE withbosses ll, this cylindrical portion 5 arrangement provides for uniform heat and stress being provided with spaces 22 to lighten the 25 conditions in the piston skirt resulting, among weight of the piston assembly, other things, in providing a low unit pressure The bosses l'l depend within the skirt body 10 engagement with the cylinder and a desirable in spaced relationship therewith. In order to stability in the thermal conditions of the piston. limit the assembly Of the head and s rtpo t 0 A further object is to provide an improved as will be presently more apparent, bosses I! are method of making and assemblying a piston, provided with seats 23 engagedby the inner end especially of the type referred to above. of flange I2.

' Further objects and advantages of my inven- Prior to assembly of the piston head andskirt.

tion will be more apparent from the following 'referring'particularly to Fig. 4, the diameter of 5 illustrative embodiment of the principles of my opening I3 is less than the diameter after asinvention, reference being bad to the accompany- 'sembly and the diameter of cylindrical portion 2| ing drawing, in which: is greater than after assembly.

Fig. lis a sectional elevational view of the pis- F r assem lyi h p rts, I subject the head ton, showing a connecting rod articulated B to a shrinking process and the skirt A to an 0 thereto. expanding process, under which .conditions the 40 Fig. 2 a sectional plan view along the line parts may be assembled preferably by the appli- 2-2 of Fig. 1. cation of a hand light pushing force. Head B is Fig.3 is a sectional elevational view along the contracted by subjecting it to commercial dry line 3-3.of Fig. 1. ice and skirt A is'expanded by subjecting it to a 5 Fig. 4 is an enlarged fragmentary sectional, hot liquid such as oil. In Fig. '4 the overlap of view'of engageable parts of the piston skirt and the eng'ageable surfaces has been exaggerated for head as seen in Fig. 3 prior to assembly of these purposes of illustration, the surface contact parts. upon assembly being indicated at 26.

Referring to the drawing, reference character As an illustration for a piston of approximately 0 A represents the skirt portion of my piston and the size illustrated in my drawing, the dia- B the head portion, these parts being preferably metrical difference or overlap between opening i 3 separately cast of a light weight alloy such as and portion Zimay be approximately .008 of an commercial Duralumin. inch so that after the aforesaid hot and cold The skirt A has a solid cylindrical main body treatments this diametrical difference will afford 5 s5.

This invention relates to pistons for use in internal combustion engines.

.One object of my invention is to provide animproved piston of relatively light weight capable of manufacture at relatively low cost.

A furtherobject is to provide a piston congt struction providing improved thermal characteristics in its operation, affording improved conditions of hot and cold running in the engine l0 preferably free from slots. holes and the like.

whereby uniform heat and stress conditions will be obtained without localized high unit pressure points when operating in the usual cylinder (not shown). At the upper end of the cylindrical body I0, the skirt A is provided with one or' more piston ring-receiving grooves II to seal'the piston against gas and oil leakage. Adjacent this grooved end, the skirt is formed'withan inwardly extending annular flange l2 providing a cylindrical a clearance of approximately .001 of an inch. .At

according to final requirements of desired fits and for other reasons.

In view of the relatively greater temperature increase of skirt A above normal room temperature compared with the temperature decrease of head B, the diameter of opening i3 will be increased more than the decrease of portion 2|, such condition being illustrated in Fig. 4 in reference to the assembly engagement at 24.

On assembly of the parts, the head portion 2| expands due to the rise in temperature and the flange l2 will contract diametrically inwardly of opening l3 whereby portion 21 will act in compression against flange I2, the latter acting in tension against portion 2i to securely hold these parts together under all conditions met with during the operation of the piston in the engine. During operation of the piston, the tight fit of the parts when the engine is cold as before starting, will be maintained and actually increased, it being recognized that the central parts of a piston face are hotter than the marginal parts. This will cause the head portion Hi to expand to a greater extent than that of flange l2.

Various modifications and changes will be apparent from the teachings of my invention, as defined in the appended claims, and it is not my intention to limit my invention to the particular details of construction and method shown and described for illustrative purposes,

I claim:

1. In a piston, a substantially cylindrical skirt portion and a grooved sealing ring receiving end portion integral therewith, said end portion including an annular radially inwardly extending marginal portion having an axially extending opening therethrough, a piston head fitting in said opening and having piston pin receiying means depending therefrom and in spaced relation to the wall of said skirt, said marginal portion and said head having end face portions cooperating to present a piston end face, said marginal portion including a depending integral annular flange spaced radially from the adjacent portion of said grooved portion and engaging said piston head, and circumferentially spaced radially extending ribs connecting said depending flange and said ring receiving end portion.

2. In a piston, a substantially cylindrical skirt po'rtion and a grooved sealing ring receiving end portion integral therewith, said end portion including an annular radially inwardly extending marginal portion having an axially extending,

opening therethrough, and a piston head fitting in said opening and having piston pin receiving means depending therefrom and in spaced relation to the wall of said skirt, said marginal portion and said head having face portions cooperating to present a piston end face, said marginal portion including a depending integralannular flange spaced radially from the adjacent portion of said grooved portion and engaging said piston head, said piston head having circumferentially 1 spaced openings in the axial periphery thereof and disposed in substantial axial alignment with said piston pin receiving means.

CHILD HAROLD WILLS. 

